Forging of multi-throw crank-shaft



Feb. 28, 1961 ROBRA FORGING OF MULTI-THROW CRANK-SHAFT 24 2 Sheets-Sheet 1 Filed May 6, 1957 my. I

I lNl/ENTOZ? H. 5)% l HTTYS.

United States Patent ronemo or MULTI-THROW' CRANK-SHAFT Helmut Robra, Mulheim (Ruhr), Germany, assignor to Schloemann Aktiengesellschaft, Dusseldorf, Germany Filed May 6, 1957, Ser. No. 657,346

Claims priority, application Germany May 16,1956- 1. "Claim. (Cl. 2 99-6),

Earlier patent applications of' the present invention relate to a. method and apparatus for the, progressive forging of multi-throw crank-shafts from a forging with pressed-in journals, between which thickenings. are provided, which are pressed flat at angles corresponding to the angular spacing of the cranks to be formed, and are then shaped into cranks. V

The object of the present invention is to improve the abovementioned apparatus. In particular it aims at making the apparatus suitable for withstanding the. great forces that are exerted in carrying out the process, while nevertheless keeping the weight of the; apparatus small. A further object of the invention. is so to construct the apparatus that those parts have to be changed for others when crank-shafts of different dimensions are to be pro duced by means of the apparatus can be exchanged easily.

Further objects of the invention can be gathered from the following description.

In known apparatus for forging the crank-throws of crank-shafts, with exchangeable lower holding members slidable on a base-plate, together with an exchangeable forging die, it is difficult to hold the lower holding members so firmly that they are able to withstand the great forces acting upon them in the direction of the shaft. These forces are particularly large when the upper holding members, which are seated on a part of the apparatus that is movable up and down, are required not to transmit to the upper member of the apparatus any appreciable forces in the direction of the shaft. The lower holding members must therefore, in most constructions, also take up the axial forces of the upper holding members. This invention provides means enabling them to do this.

The invention consists in the feature that the baseplate is of box-like construction, and accommodates within itself the lower holding members, with the forging die, and also exchangeable spacing members. The edges of the box-like base-plate, since they constitute a unitary casting with the base-plate, are able to take up the axial forces well and reliably. The box-like construction of the base-plate also facilitates the clamping of the holding members and of the forging die in an axial direction, besides securing them against lifting; such securing being necessary when the press ram, which cooperates with the said forging die, is drawn upwards, or the finished shaft is lifted out of the lower holding members.

Further features of the invention will be gathered from the following description of one constructional example, illustrated in the accompanying drawings, in which:

Figure 1 shows an end view of a machine according to the invention, looking in the direction II in Figure 2;

Figure 2 shows a plan of the lower part of the apparatus after removal of the upper part, on about the line IIII in Figure 1;

Figure 3 shows a section on the line IIIIII in Figure 2;

Figure 4 shows a partial view of the under part of the apparatus, looking in the direction of the arrow IV in Figure 2; and

ice

Figures 5 shows a. partial. section on the line VV in Figure 2.

The apparatus consists of a lower part 1, including a base-plate 1a, and an upper part 2, which can be attached to the cross-beam of a forging press, by means for example of keyways 2a. Thev upper partz has in the center an opening through which the press ram 3 can be introduced from above, which, co-operating with the forging die ,4, forges a crank-throw of the crank-shaft. The under. part 1 of. the apparatus-is box-shaped, and may be constructed in one piece, as shown more particularly by Figures 3, 4 and 5. In addition to the base-plate 1a it has twolongitudinal walls 1b., which, merge into end walls provided with niches 1c. The niches 1c accommodate outer wedge-shaped fitting pieces or guard plates 20. To each of the end walls. is allocated agroup of keys, each consistingof two vertical keys 7a and 7band a horizontal key 70. These three keys bear at one side on the outer wedge-shaped fitting piece 20.. The opposite sides of the. keys 7a, 7b and 7c bear against an inner wedgeshaped fitting piece 21, the opposite. side of which is in contact with a spacing member 6d. Then follows a holding member 5, which in its turn is followed by further spacing members 611, 6b, 6c, and a further holding member 5a.. About midway along the. length of the under part 1 ofv the apparatus aiforging die 4 is arranged. On. the other side of the forging die 4- asimilar series of spacing members, holding members and wedge-shaped fitting pieces are provided in corresponding sequence. The wedge-shaped fitting piece 20, which is located in the niche 1c of the end wall, may also be regarded as a guard plate, since it serves to protect the niche wall against becoming worn by the keys or wedges 7a, 7b, 7c.

The spacing members 611, 6b, 6c serve for maintaining the spacing between the holding members 5 and 5a and between the holding members 5b and 5c; and the spacing member 6d serves for filling up the space between the inner wedge-shaped fitting member 21 and the outer holding member 5 or 5c. The thickness of the holding members and of the spacing members to be employed in each particular instance is determined according to the dimensions of the Work-piece to be produced and according to the thickness of the forging die. In fact the purpose of sub-dividing the spacing members is just to obtain the desired distance between the holding members 5, 5a, 5b, 50 by suitable combinations of a number of spacing members.

The assembling and clamping of the die, the holding members and the spacing members is effected as follows:

First of all the forging die 4 is placed in the under part 1 of the apparatus, its height being adjusted by means of shims. The position of the forging die 4 is fixed in accordance with that of the forked press ram 3. The holding members and spacing members arenow inserted on both sides of the forging die, without altering the position of the latter. Against the free end surfaces of the last inserted spacing members at both ends are now inserted the inner wedge-shaped fitting pieces 21, and thereupon, beside them, the outer wedge-shaped fitting pieces 20, and between the two, in each case, a group of three keys 7a, 7b and 7c. By tightening the keys, all the members located between the two groups of keys are clamped, the outer fitting pieces 20 serving as abutments for the groups of keys, and being supported in the niches 1c of the end walls of the under part 1 of the apparatus.

Since there would be a risk that the forging die 4, as the press ram 3 is being raised after the forging of a crank throw, might be torn out of the under part 1 of the apparatus, it is held fast by horizontal sliding bolts 8. Each sliding bolt can be released when required by knocking out a wedge 8a. T o the holding members 5, 5a, 5b and 3 5c are allocated flat sliding bolts 9, which can each be pushed in and out by means of a spindle 10, with a handwheel 11. These flat sliding bolts 9 serve the same purpose as the sliding bolts 8.

The appliance illustrated render possible not only an accurate holding of the holding members 5, 5a, 5b and 5c, for the purpose of taking up the heavy axial forces during the forging but also render possible a quick rearrangement of the apparatus when there is to be a transition from one form of crank to another.

I claim:

Apparatus for successively forging the crank-throws of a crank shaft on which central journals have been I previously formed, comprising a base plate, semicircularly recessed exchangeable lower holding members displaceable and securable on the base plate, sernicircularly recessed spacing members between the holding members, an exchangeable forging die adapted to be secured against upward movement relatively to the base plate, a vertically movable press ram adapted to co-operate with the forging die to forge a single crank throw, two side walls formed integral with the base plate and having top surfaces level with the upper extremities of the forging die, of the spacing members and of the holding members, two end walls formed integral with the side walls and base plate and having a height substantially equal to that of the holding members, a cover apertured to permit the passage of the press ram and adapted to rest on top of the walls of the base plate during movement of the ram relatively to the die, semicircularly recessed upper hold- 30 ing members mounted in the cover member and adapted to co-operate with the lower holding members to define apertures surrounding the central journals of the shaft, a

' niche in each end wall of the base plate, and at each end inner and the outer fitting pieces and projecting above the tops of the fitting pieces, whereby the holding members, the spacing members and the press die are clamped in the longitudinal direction of the base plate and the clamping action is exerted over substantially the whole of the height ofthe holding members.-

References Cited in the file of this patent UNITED STATES PATENTS 140,567 York July 1, 1873 647,367 Blakeslee Apr. 10, 1900 1,426,784 Solmson Aug. 22, 1922 1,977,163 Wilcox July 22, 1933 2,653,373 Brauchler Sept. 29, 1953 2,688,793 Carlson Sept. 14, 1954 FOREIGN PATENTS 352,946 Germany May 9, 1922 

